3D Text diffuse shader?

Hello! I've been trying to make a quick prototype for a card game, but I've come across an issue. I'm using 3D text meshes for the card numbers, and when they are under a shadow they (expectedly) keep their original text color. I'm looking for a way to make/find a 3D text diffuse shader for this case.

This is the issue:

This is my 3D text shader:

 Shader "GUI/3D Text Shader" { 
     Properties {
         _MainTex ("Font Texture", 2D) = "white" {}
         _Color ("Text Color", Color) = (1,1,1,1)
     }
  
     SubShader {
         Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }
         Cull Off ZWrite Off Fog { Mode Off }
         Blend SrcAlpha OneMinusSrcAlpha
         Pass {
             Color [_Color]
             SetTexture [_MainTex] {
                 combine primary, texture * primary
             }
         }
     }
 }

Is there any easy answer to this issue? Thanks in advance!